The invention relates to a steering wheel for a motor vehicle according to the preamble of Patent claim 1.
Such a steering wheel comprises a steering wheel rim for rotating actuation of the steering wheel by a driver as well as a steering wheel hub via which the steering wheel can be connected with a steering shaft, which is separate from the steering wheel and can be rotated, so that a rotation movement of the steering wheel rim is converted into a corresponding rotation movement of the steering shaft. The steering wheel rim and the steering wheel hub are connected here, e.g. via spokes.
Furthermore, a superposition drive is provided on the steering wheel for the actuation of a superposition steering by means of which said steering a steering angle created by a driver's actuation of the steering wheel rim can be superposed by a superposed angle created by the superposition steering, so that a respective rotation movement of the steering shaft—referring to the state of the steering shaft in which it is connected with the steering wheel—is composed of a steering angle created by a driver's actuation of the steering wheel rim and a superposed angle created by actuation of the superposition steering, wherein the latter angle makes no contribution in case of a deactivation of the superposition steering.
Such a steering wheel is familiar from WO 2007/009420 A1. Herein, the superposition drive comprises two drive motors (electric motors), each one integrated into one spoke of the steering wheel respectively, which said motors can, each one via one worm respectively, act upon a central gear element of the superposition drive in the form of a worm gear on the output drive side. Via this gear element on the output drive side the superposition drive in turn stands in connection with an allocated steering shaft of a motor vehicle in such a way that a moment created by the drive motor of the superposition drive can be conveyed into the steering shaft to rotate said shaft on a specific superposed angle—in addition to a steering angle created by a driver's actuation of the steering wheel rim.
A further variant of a superposition drive for a superposition steering with a drive motor and a gearing subordinate to the drive motor is familiar from DE 101 60 313 A1, wherein this superposition drive is located outside of the steering wheel between a steering shaft portion on the input side that is connected with the steering wheel and a steering shaft portion on the output side that is connected with the steering gear of a motor vehicle. For this reason, additional installation space is needed in the area of the steering column surrounding the steering shaft for the housing of the superposition steering, which requires a corresponding configuration of the steering column.